1. Field of the Invention
This invention relates to a novel nitrogen-containing perfluoroalkyl bromide and a method for the production thereof. More particularly, this invention relates to a nitrogen-containing perfluoroalkyl bromide which is useful as an intermediate for the synthesis of fluorine-containing products such as surfactants, agricultural pesticides, and medicines, as a halon type fire extinguisher gas, as a flame-retarding additive for transformer oil and electric insulating oil, and as an X-ray contrast medium, and to a method for producing this compound economically from a readily available raw material in a high yield.
2. Prior Art Statement
A perfluoroalkyl bromide has a relatively weak bond between the perfluoroalkyl group and the bromine thereof. This bond easily cleaved. It is therefore known as a compound for the introduction of a perfluoroalkyl group and is used as the raw material for the synthesis of fluorine-containing products such as surfactants, agricultural pesticides, and medicines. It is further useful by itself as a halon type fire extinguisher gas, as a flame-retarding additive for transformer oil and electric insulating oil, and as an X-ray contrast medium, for example.
Recently, since such undecomposable CFC and halon type compounds are thought to deplete the ozone layer, their use is being phased out. Efforts are therefore being devoted to the development of substitutes for these compounds. The substitutes for the sparingly decomposable halon type compounds which are now widely used in gaseous type fire extinguishers are required to decompose before reaching the stratosphere.
As decomposable, halon compounds, there have been developed hydrofluorobromocarbon (HFBC) and hydrofluorocarbon (HFC). These are produced by the introduction of hydrogen atoms into perfluoro compounds, which gives them appropriate decomposability. Further as compounds useful for the protection of the ozone layer and the prevention of global warming, the development of fluorine compounds made decomposable by the introduction of hetero atoms have also been proposed ["Introduction to Chemistry", No. 11, page 94 (1991)].
A nitrogen-containing perfluoroalkyl bromide has the various properties required of a halon compound substitute and, therefore, is expected to find acceptance as a new type fire extinguisher gas. Methods for producing specific nitrogen-containing perfluoroalkyl bromides known to the art to date include: a method which produces perfluoro(N,N-dimethyl-2-bromoethyl amine) by exposing N-bromo-bis-trifluoromethyl)amine and tetrafluoroethylene to sunlight at 25.degree. C. for a long time ["Journal of Chemical Society", page 6,141 (1965)], a method which produces perfluoro(N,N-dimethyl-2-bromopropyl amine) by causing N-bromo-bis(trifluoromethyl)amine to react with hexafluoropropene at 100.degree. C. for 24 hours ["Journal of American Chemical Society", Vol. 80, page 3,604], and a method which produces a nitrogen-containing perfluoroalkyl bromide by causing a nitrogen-containing perfluorocarboxylic acid fluoride to react with lithium bromide at a temperature in the range of from 200.degree. to 500.degree. C. (Japanese Patent Application No. 82729/1989) . The products obtained by these methods are compounds having a bromine atom bonded to the .beta.-carbon atom of perfluoroamine.
Thus, there is a need for the development of novel nitrogen-containing perfluoroalkyl bromides with more extensive utility than the known nitrogen-containing perfluoroalkyl bromides, as intermediates for the synthesis of surfactants, agricultural pesticides, and medicines, as a halon type fire extinguisher gas, as a flame-retarding additive for transformer oil and electric insulating oil, and as an X-ray contrast medium.